Scotgen powers up with gasification trailblazer

Scotgen believes its thermal treatment plant in Dargavel will become a blueprint for other facilities in the future. Claire Smith went to the opening to find out more

It is no bigger than an out-of-town DIY superstore, but the Scotgen plant just outside Dumfries is Scotland's newest power station. The waste-to-energy thermal treatment plant built using Icelandic technology claims to be the first of its kind in the UK, but the company believes it will become one of many.

Using fuel made from household waste, the £20M plant began generating electricity in August. Project director Lloyd Brotherton - who works for Ascot Environmental, the main contractor on the project - explains that the compact thermal generating plant was set up to process the solid recovered fuel (SRF) produced by Shanks, which has the contract to process household waste for Dumfries & Galloway Council.

"When the PFI was put out, the idea was always to have some kind of thermal processing plant at the end of it. The planning permission was already in place and local support has been great," he says. The new plant will also process contaminated and non-hazardous waste, such as oily rags and fertiliser bags. The idea is to reprocess waste from the Southwest of Scotland and for this type of compact processing plant to be reproduced to serve other local areas.

Waste materials or SRF is loaded into big metal bins that are then sealed and the contents set alight. Once the temperature reaches 450˚C, the hot gases travel to a secondary chamber where temperatures reach more than 11,000˚C. The heat is used to create steam that then powers a £2M Siemens turbine, which generates electricity.

The new plant employs 18 staff who will work a 24-hour continental shift system.

Scotgen now has the contract to handle a minimum of 15,000 tonnes of SRF a year from Dumfries and Galloway. The capacity of the plant is 40,000 tonnes of waste a year - but if demand increases, there is space to introduce a third stream and expand this to 60,000 tonnes.

Significant scale"Gasification is not new, but what is significant is the scale," explains Brotherton. "Each of our streams can take 20,000 tonnes a year and we can take pretty much anything. We don't need a big quantity, which means we can also be used as a testing ground. We are running it on an open basis, which means if somebody has waste they can send us 60 tonnes and use it as a test bed. This is the first one of its type. It is a sequential batch gasification system. We load the machines every six hours."

As well as reducing the need to use landfill, the Scotgen plant also has the advantage of cutting down transport costs and pollution. Before it opened, SRF from Dumfries and Galloway household waste was being transported down to the Southwest of England and to Wales to be reprocessed. Having the plant on the outskirts of Dumfries means that household waste can be sorted, processed and turned into electricity without having to be transported for miles across the country.

Recycling won't be sidelinedBrotherton insists the plant won't have a negative impact on recycling. "All the recyclable products are taken out of the waste before it gets turned into SRF. Dumfries and Galloway is not blessed with a multitude of landfill sites, and so why not use residual waste as fuel rather than bury it in a landfill?"

Scotgen has already sold the first year's crop of electricity through the Scottish Non Fossil Fuel Purchasing Authority. Big power companies are keen to buy fuel made from recycled waste because it helps them meet government targets for renewable energy. The plant has the capacity to generate 15MW of power a year.

The company is looking for a purchaser for excess heat produced by the plant - which can be transported up to a mile and a half away from the site and will ideally be used to supply local industries. Local businesses such as fish farms and greenhouses are being considered. Uses are also being sought for the residual ash, which will be left after the waste has burnt out.

Scotgen has been pleased with the level of local support for the plant and has tried to use local contractors wherever possible. Although the big bins were imported from Iceland, the boilers were made by Cochrane's of Annan. Maintenance work will be carried out by local contractors wherever possible.

Andy Carey, facility director for Scotgen, who previously helped oversee the PFI project with Shanks, is delighted the final piece of the Dumfries and Galloway recycling jigsaw is in place. "It's exciting. We are reducing landfill, which has to be the way forward. My role is to make this plant successful, but also to make this a torch for other sites to be built in the future."